For the past few months, my home church has been going through the apostle John's "The Revelation of Jesus Christ" during the main preaching service. A few weeks ago, I was privileged to lead an adult class immediately after one of the sermons on Revelation.
Taking a macro view of things (as I am wont to do), I encouraged that class to view the grand arc of the history of time from God's perspective. My organizing outline can be summarized with three Cs. They are:
the Cosmic war
the Cross of Christ
the Church of God
"In the beginning God." Before His creation of the material universe and before His creation of the angels, God existed as the "Great I Am." Eternally existent, God is complete in Himself, and He neither needs nor is He somehow completed by having created finite and sentient beings.
The mighty angels He brought into existence, who in the Bible are alternately called "Sons of God," "ministering spirits," "winds," "ministers and flames of fire," "holy angels," and more, were and are the first finite beings to worship and serve the living God. This was only fitting and proper, since God is infinitely worthy to be worshiped and served.
When Lucifer rebelled against God and was cast out of heaven along with perhaps a third of the angelic host who allied themselves with him, a war of cosmic proportions erupted in God's universe. This is the first C of my "three-point sermon(!)." Christians must not fail to see this aspect of the "big picture."
While theodicy is beyond the scope of my answer, I will suggest that any good theodicy has to deal somehow with God's having created sentient beings to whom He gave volition. There is something in the character of God that prompted Him to give both the celestial and terrestrial beings whom He created in His image (yes, the angels were in some sense created in His image) the ability to choose freely to worship and serve Him.
Lucifer and his cohorts chose not to fulfill their God-given privilege and responsibility of worshiping and serving YHWH and were thus cast out of heaven. Since then, Satan (Ge 3:1-5; 1 Ch 21:1; Job 1 and 2; Ze 3:1,2) and his minions have been actively opposing the purposes and plans of God through an organized campaign born of hatred for God and carried out through sin, deception, temptation, death, and destruction. Praise God, Jesus came to destroy the works of the devil (1 Jn 3:8), and His plan to do so came to fruition in a way that is not only consistent with His holy and perfect character; moreover it cannot be defeated, which brings us to the second C: the cross of Christ.
Jesus, the eternally begotten Son of the eternal God, is described in Scriptures as a lamb that was slain before the foundation/creation of the world (1 Pe 1:19,20), whose shed blood cleanses and redeems those who, unlike the devil, choose to obey the truth as it is found in the One who described Himself as the truth (Jn 14:6).
In the mind of God, the outcome of the war between the host of evil and God (and the people of God) is a fait accompli. In that sense, then, "the ruler of this world will be cast/driven out" (Jn 12:31). This casting out of Satan began in eternity past, was accomplished judicially at the cross of Christ (which by the way provides the context for John 12:31), and will be completed someday in time and space (see Re 20:3,10).
In the John 12 passage, the Greek word for "cast out" or "driven out" is ekballo, and ballo is the Greek word for "threw" or "thrown" in the Revelation 20 passage. There is therefore both a past- and a future aspect to Satan's being cast/driven/thrown out by God. Much more important of the two, in my opinion, is the casting out that occurred at the cross and subsequent resurrection, where Christ triumphed over the hosts of evil and led captivity captive, having
"made a public spectacle of them, triumphing over them by the cross" (Col 2:15).
At the cross Jesus disarmed the infernal powers and authorities. At the cross God dealt Satan a death blow, the crushing of Satan's head foretold in Ge 3:15, There is still work to be done, however, which brings us to the third C: the Church of God.
In the interim between the cross, on the one hand, and God's new heaven and new earth in which only righteousness dwells--free of sin and unrighteousness forever (Re 21:1), on the other hand, there is the Church Age. While Satan and his minions have been stripped of their armor (which is perhaps a better description of what Paul meant by his term "disarmed" in Colossians 2:15) and are thus subject to Christ and His Church in a way that could not and would not have been possible apart from the death and resurrection of Christ, they are not totally impotent.
Today, God is in the process of building His Church Universal, of which Jesus said,
" . . . and on this rock [i.e., that Jesus is the Christ, the Son of the living God] I will build my church, and the gates of Hell will not overcome it" (Mt 16:15-18).
In a sense (and covenant theologians may disagree with me on this point), the Church Age had its beginning on the day of Pentecost, and it will have its consummation at the wedding feast of the Lamb, where Christ's bride, the Church, will be united to her groom in an eternal marriage. That marriage is an "arranged" marriage, by the way, and it was arranged in eternity past by an all wise and all loving God who in love is calling out from the world that is temporarily under the influence of its god--small G--a people from every tongue and tribe who by obeying the gospel of His Son are destined for glory in heaven forever.
Remember, a god with a small G is no match for God with a capital G. The teaching of Scripture is clear: the ultimate defeat in time and space of the god of this world system (< Gk. cosmos) is assured, and the defeat of the various gods/idols he offers humanity, which are in reality no gods, is also assured. In the meantime God is building His Church one living stone at a time, until the superstructure, which is based on Christ, the chief cornerstone, is completed (1 Pe 2:4-10).
That Church--a spiritual house, a holy priesthood, a chosen people, a royal priesthood, a people belonging to God--is being called out of darkness and into God's wonderful light. Until the last living stone is finally added to the Church, God's people still have to struggle with the world system and its many idols, all of which are summed up in John's big three:
"the lust of the flesh, the lust of the eyes, and the pride of life" (1 Jn 1:15-17).
Christ's Church, however, will ultimately be victorious, and we have Jesus' word on it (Mt 16:17)!